Andrey Kuzmin <andrey.v.kuz...@gmail.com> writes: > Darren J Moffat wrote: >> Andrey Kuzmin wrote: >>> Resilvering has noting to do with sha256: one could resilver long >>> before dedupe was introduced in zfs. >> >> SHA256 isn't just used for dedup it is available as one of the >> checksum algorithms right back to pool version 1 that integrated in >> build 27. > > 'One of' is the key word. And thanks for code pointers, I'll take a > look.
I didn't mention sha256 at all :-). the reasoning is the same no matter what hash algorithm you're using (fletcher2, fletcher4 or sha256. dedup doesn't require sha256 either, you can use fletcher4. the question was: why does data have to be compressed before it can be recognised as a duplicate? it does seem like a waste of CPU, no? I attempted to show the downsides to identifying blocks by their uncompressed hash. (BTW, it doesn't affect storage efficiency, the same duplicate blocks will be discovered either way.) -- Kjetil T. Homme Redpill Linpro AS - Changing the game _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
